A Procedure to Detect Item Bias Present Simultaneously in Several Items
Technical rept. 1988-1991
ILLINOIS UNIV AT URBANA DEPT OF STATISTICS
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This paper presents a statistical procedure denoted by SIB designed to test for undirectional test bias existing simultaneously in several items of an ability test. It was argued in Shealy and Stout 1991 that in order to model such bias with an IRT model, a multidimensional model is necessary. The proposed procedure, based on this multidimensional IRT modeling approach, statistically tests for bias in one or more items at a time and is corrected for the inflation or deflation of the test statistic due to target ability difference, a valid group difference that is conceptually independent of psychological test bias. The correction plays the same role as the practice of including the single studied item in the matching criterion score in the Mantel-Haenszel MH procedure adapted for test responses by Holland and Thayer 1988. It is shown through the initial portion of an extensive simulation study underway Shealy 1991 that, with the correction in place, the procedure performs as well as the MH procedure in many cases when there is a single biased item, and performs well in the case of multiple item test bias.
- Statistics and Probability